1. Field
The present invention relates generally wireless power transfer, and more specifically, to systems, device, and methods for conveying energy from a wireless power receiver to a load.
2. Background
Approaches are being developed that use over the air power transmission between a transmitter and the device to be charged. These generally fall into two categories. One is based on the coupling of plane wave radiation (also called far-field radiation) between a transmit antenna and receive antenna on the device to be charged which collects the radiated power and rectifies it for charging the battery. Antennas are generally of resonant length in order to improve the coupling efficiency. This approach suffers from the fact that the power coupling falls off quickly with distance between the antennas. So charging over reasonable distances (e.g., >1-2 m) becomes difficult. Additionally, since the system radiates plane waves, unintentional radiation can interfere with other systems if not properly controlled through filtering.
Other approaches are based on inductive coupling between a transmit antenna embedded, for example, in a “charging” mat or surface and a receive antenna plus rectifying circuit embedded in the host device to be charged. This approach has the disadvantage that the spacing between transmit and receive antennas must be very close (e.g. mms). Though this approach does have the capability to simultaneously charge multiple devices in the same area, this area is typically small, hence the user must locate the devices to a specific area.
As will be understood by a person having ordinary skill in the art, conventional wireless power receivers may use a two-step process to supply DC power to a load. More specifically, a conventional wireless power receiver may use a rectifier along with a DC-to-DC converter to supply DC power to a load. A need exists to increase wireless power transfer. More specifically, a need exists for enhanced methods, devices, and systems for providing power from a receiver to a load.